1. Field of the Invention
The present invention relates to a power converter.
2. Description of the Related Art
In recent years, as power converters, inverters having higher power density are demanded. A power converter system, used in a data center, includes a plurality of power converters that have common and integrated components to facilitate an attempt to achieve a compact, lightweight, and low cost system.
During maintenance, a worker takes out a subject power converter from the power converter system, and performs work such as exchanging and maintenance. Then, the worker attaches a new power converter or the power converter after the maintenance work to the power converter system. Here, the power converter needs to be detached and attached while the power converter system is operating, and thus needs to be what is known as hot swappable power converter.
When the hot swapping of the power converter from the power converter system is performed, inrush current to a capacitor in the power converter needs to be limited to prevent the capacitor from being broken by the inrush current. Thus, the power converter is provided with an inrush current limiting circuit that limits the inrush current to the capacitor (Japanese Patent Application Laid-open No. 2009-11042 and Japanese Patent Application Laid-open No. 2014-14273).
In a conventional technique described in Japanese Patent Application Laid-open No. 2009-11042, a charging resistor and a relay switch are connected in parallel with the capacitor. Thus, when a connection with a grid is established, pre-charging of the capacitor is performed through the charging resistor, and when the charging is completed, the relay switch is turned ON, whereby the capacitor is connected to the grid through the relay switch.
In a conventional technique described in Japanese Patent Application Laid-open No. 2014-14273, the relay switch and the charging resistor are provided in a power semiconductor unit. When the hot swapping is performed, voltage at both ends of the capacitor in the power semiconductor unit is detected, and in accordance with this voltage at both ends, switching between the relay switch and the charging resistor is performed.